1. Field of the Invention
The present invention relates to a mura detection apparatus and method for detecting an image-quality distortion of a display device.
2. Discussion of the Related Art
As liquid crystal display (LCD) devices are enlarged in size, the size and frequency of occurrence of a mura defect, namely, a smear defect and an image-quality distortion, are increasing. Mura denotes a smear in Japanese, and denotes a defect in which when an entire screen is displayed at a constant gray scale, a specific area is non-uniformly displayed.
A related art mura detection method determines all defects, in which a contrast of a boundary is visible irrespective of a form and size of a defect, as mura. A mura defect is generally determined by an inspection using a user's eyes, but as LCD devices are enlarged in size, the existing method has a limitation in detecting the mura defect. Also, in the inspection using a user's eyes, a degree of detection of mura can be differently shown depending on a worker's workmanship, and as a screen size is enlarged, a deviation of mura detection increases
FIG. 1 is a diagram schematically illustrating a related art mura detection method.
Referring to FIG. 1, a mura inspection method using SEMU developed by Semiconductor Equipment and Materials International (SEMI) was proposed for improving a mura inspection method based on a user's subjectivity.
To describe the related art mura detection method using SEMU, the mura detection method preprocesses input image data, and then displays an image in a display panel in operation S1.
Subsequently, the mura detection method inspects mura displayed in the display panel with eyes to detect a mura candidate area in operation S2.
Subsequently, a worker checks a luminance difference with respect to the background in the mura candidate area to determine the final mura, and classifies the mura by kind in operation S3.
The related art mura detection method removed a user's subjective error factor, but has a problem that a noise is detected as mura due to a non-uniformity of a luminance, caused by a characteristic of an LCD device, and foreign materials remaining in a panel.
In addition, despite that mura can occur due to various factors and features of mura candidate areas can differ, the related art cannot reflect the significance of the various features. Especially, spot-shaped mura (circular mura and oval mura) such as a black spot, a white spot, and a black-and-white spot can occur, but the existing inspection method using a worker's eyes cannot precisely detect and classify spot-shaped mura.